package io.github.bedwarsrel.utils;

/*
 * Copyright 2011-2013 Tyler Blair. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation are those of the authors
 * and contributors and should not be interpreted as representing official policies, either
 * expressed or implied, of anybody else.
 */

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.net.Proxy;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.UUID;
import java.util.logging.Level;
import java.util.zip.GZIPOutputStream;
import org.bukkit.Bukkit;
import org.bukkit.Server;
import org.bukkit.configuration.InvalidConfigurationException;
import org.bukkit.configuration.file.YamlConfiguration;
import org.bukkit.entity.Player;
import org.bukkit.plugin.Plugin;
import org.bukkit.plugin.PluginDescriptionFile;
import org.bukkit.scheduler.BukkitTask;

public class McStatsMetrics {

  /**
   * The base url of the metrics domain
   */
  private static final String BASE_URL = "http://report.mcstats.org";
  /**
   * Interval of time to ping (in minutes)
   */
  private static final int PING_INTERVAL = 15;
  /**
   * The url used to report a server's status
   */
  private static final String REPORT_URL = "/plugin/%s";
  /**
   * The current revision number
   */
  private final static int REVISION = 7;
  /**
   * The plugin configuration file
   */
  private final YamlConfiguration configuration;
  /**
   * The plugin configuration file
   */
  private final File configurationFile;
  /**
   * Debug mode
   */
  private final boolean debug;
  /**
   * All of the custom graphs to submit to metrics
   */
  private final Set<Graph> graphs = Collections.synchronizedSet(new HashSet<Graph>());
  /**
   * Unique server id
   */
  private final String guid;
  /**
   * Lock for synchronization
   */
  private final Object optOutLock = new Object();
  /**
   * The plugin this metrics submits for
   */
  private final Plugin plugin;
  /**
   * The scheduled task
   */
  private volatile BukkitTask task = null;

  public McStatsMetrics(final Plugin plugin) throws IOException {
    if (plugin == null) {
      throw new IllegalArgumentException("Plugin cannot be null");
    }

    this.plugin = plugin;

    // load the config
    configurationFile = getConfigFile();
    configuration = YamlConfiguration.loadConfiguration(configurationFile);

    // add some defaults
    configuration.addDefault("opt-out", false);
    configuration.addDefault("guid", UUID.randomUUID().toString());
    configuration.addDefault("debug", false);

    // Do we need to create the file?
    if (configuration.get("guid", null) == null) {
      configuration.options().header("http://mcstats.org").copyDefaults(true);
      configuration.save(configurationFile);
    }

    // Load the guid then
    guid = configuration.getString("guid");
    debug = configuration.getBoolean("debug", false);
  }

  /**
   * Appends a json encoded key/value pair to the given string builder.
   */
  private static void appendJSONPair(StringBuilder json, String key, String value)
      throws UnsupportedEncodingException {
    boolean isValueNumeric = false;

    try {
      if (value.equals("0") || !value.endsWith("0")) {
        Double.parseDouble(value);
        isValueNumeric = true;
      }
    } catch (NumberFormatException e) {
      isValueNumeric = false;
    }

    if (json.charAt(json.length() - 1) != '{') {
      json.append(',');
    }

    json.append(escapeJSON(key));
    json.append(':');

    if (isValueNumeric) {
      json.append(value);
    } else {
      json.append(escapeJSON(value));
    }
  }

  /**
   * Escape a string to create a valid JSON string
   */
  private static String escapeJSON(String text) {
    StringBuilder builder = new StringBuilder();

    builder.append('"');
    for (int index = 0; index < text.length(); index++) {
      char chr = text.charAt(index);

      switch (chr) {
        case '"':
        case '\\':
          builder.append('\\');
          builder.append(chr);
          break;
        case '\b':
          builder.append("\\b");
          break;
        case '\t':
          builder.append("\\t");
          break;
        case '\n':
          builder.append("\\n");
          break;
        case '\r':
          builder.append("\\r");
          break;
        default:
          if (chr < ' ') {
            String t = "000" + Integer.toHexString(chr);
            builder.append("\\u" + t.substring(t.length() - 4));
          } else {
            builder.append(chr);
          }
          break;
      }
    }
    builder.append('"');

    return builder.toString();
  }

  /**
   * GZip compress a string of bytes
   */
  public static byte[] gzip(String input) {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    GZIPOutputStream gzos = null;

    try {
      gzos = new GZIPOutputStream(baos);
      gzos.write(input.getBytes("UTF-8"));
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      if (gzos != null) {
        try {
          gzos.close();
        } catch (IOException ignore) {
        }
      }
    }

    return baos.toByteArray();
  }

  /**
   * Encode text as UTF-8
   *
   * @param text the text to encode
   * @return the encoded text, as UTF-8
   */
  private static String urlEncode(final String text) throws UnsupportedEncodingException {
    return URLEncoder.encode(text, "UTF-8");
  }

  /**
   * Add a Graph object to BukkitMetrics that represents data for the plugin that should be sent to
   * the backend
   *
   * @param graph The name of the graph
   */
  public void addGraph(final Graph graph) {
    if (graph == null) {
      throw new IllegalArgumentException("Graph cannot be null");
    }

    graphs.add(graph);
  }

  /**
   * Construct and create a Graph that can be used to separate specific plotters to their own graphs
   * on the metrics website. Plotters can be added to the graph object returned.
   *
   * @param name The name of the graph
   * @return Graph object created. Will never return NULL under normal circumstances unless bad
   * parameters are given
   */
  public Graph createGraph(final String name) {
    if (name == null) {
      throw new IllegalArgumentException("Graph name cannot be null");
    }

    // Construct the graph object
    final Graph graph = new Graph(name);

    // Now we can add our graph
    graphs.add(graph);

    // and return back
    return graph;
  }

  /**
   * Disables metrics for the server by setting "opt-out" to true in the config file and canceling
   * the metrics task.
   */
  public void disable() throws IOException {
    // This has to be synchronized or it can collide with the check in the task.
    synchronized (optOutLock) {
      // Check if the server owner has already set opt-out, if not, set it.
      if (!isOptOut()) {
        configuration.set("opt-out", true);
        configuration.save(configurationFile);
      }

      // Disable Task, if it is running
      if (task != null) {
        task.cancel();
        task = null;
      }
    }
  }

  /**
   * Enables metrics for the server by setting "opt-out" to false in the config file and starting
   * the metrics task.
   */
  public void enable() throws IOException {
    // This has to be synchronized or it can collide with the check in the task.
    synchronized (optOutLock) {
      // Check if the server owner has already set opt-out, if not, set it.
      if (isOptOut()) {
        configuration.set("opt-out", false);
        configuration.save(configurationFile);
      }

      // Enable Task, if it is not running
      if (task == null) {
        start();
      }
    }
  }

  /**
   * Gets the File object of the config file that should be used to store data such as the GUID and
   * opt-out status
   *
   * @return the File object for the config file
   */
  public File getConfigFile() {
    // I believe the easiest way to get the base folder (e.g craftbukkit set via -P) for plugins to
    // use
    // is to abuse the plugin object we already have
    // plugin.getDataFolder() => base/plugins/PluginA/
    // pluginsFolder => base/plugins/
    // The base is not necessarily relative to the startup directory.
    File pluginsFolder = plugin.getDataFolder().getParentFile();

    // return => base/plugins/PluginMetrics/config.yml
    return new File(new File(pluginsFolder, "PluginMetrics"), "config.yml");
  }

  /**
   * Gets the online player (backwards compatibility)
   *
   * @return online player amount
   */
  private int getOnlinePlayers() {
    try {
      Method onlinePlayerMethod = Server.class.getMethod("getOnlinePlayers");
      if (onlinePlayerMethod.getReturnType().equals(Collection.class)) {
        return ((Collection<?>) onlinePlayerMethod.invoke(Bukkit.getServer())).size();
      } else {
        return ((Player[]) onlinePlayerMethod.invoke(Bukkit.getServer())).length;
      }
    } catch (Exception ex) {
      if (debug) {
        Bukkit.getLogger().log(Level.INFO, "[Metrics] " + ex.getMessage());
      }
    }

    return 0;
  }

  /**
   * Check if mineshafter is present. If it is, we need to bypass it to send POST requests
   *
   * @return true if mineshafter is installed on the server
   */
  private boolean isMineshafterPresent() {
    try {
      Class.forName("mineshafter.MineServer");
      return true;
    } catch (Exception e) {
      return false;
    }
  }

  /**
   * Has the server owner denied plugin metrics?
   *
   * @return true if metrics should be opted out of it
   */
  public boolean isOptOut() {
    synchronized (optOutLock) {
      try {
        // Reload the metrics file
        configuration.load(getConfigFile());
      } catch (IOException ex) {
        if (debug) {
          Bukkit.getLogger().log(Level.INFO, "[Metrics] " + ex.getMessage());
        }
        return true;
      } catch (InvalidConfigurationException ex) {
        if (debug) {
          Bukkit.getLogger().log(Level.INFO, "[Metrics] " + ex.getMessage());
        }
        return true;
      }
      return configuration.getBoolean("opt-out", false);
    }
  }

  /**
   * Generic method that posts a plugin to the metrics website
   */
  private void postPlugin(final boolean isPing) throws IOException {
    // Server software specific section
    PluginDescriptionFile description = plugin.getDescription();
    String pluginName = description.getName();
    boolean onlineMode = Bukkit.getServer().getOnlineMode(); // TRUE if online mode is enabled
    String pluginVersion = description.getVersion();
    String serverVersion = Bukkit.getVersion();
    int playersOnline = this.getOnlinePlayers();

    // END server software specific section -- all code below does not use any code outside of this
    // class / Java

    // Construct the post data
    StringBuilder json = new StringBuilder(1024);
    json.append('{');

    // The plugin's description file containg all of the plugin data such as name, version, author,
    // etc
    appendJSONPair(json, "guid", guid);
    appendJSONPair(json, "plugin_version", pluginVersion);
    appendJSONPair(json, "server_version", serverVersion);
    appendJSONPair(json, "players_online", Integer.toString(playersOnline));

    // New data as of R6
    String osname = System.getProperty("os.name");
    String osarch = System.getProperty("os.arch");
    String osversion = System.getProperty("os.version");
    String java_version = System.getProperty("java.version");
    int coreCount = Runtime.getRuntime().availableProcessors();

    // normalize os arch .. amd64 -> x86_64
    if (osarch.equals("amd64")) {
      osarch = "x86_64";
    }

    appendJSONPair(json, "osname", osname);
    appendJSONPair(json, "osarch", osarch);
    appendJSONPair(json, "osversion", osversion);
    appendJSONPair(json, "cores", Integer.toString(coreCount));
    appendJSONPair(json, "auth_mode", onlineMode ? "1" : "0");
    appendJSONPair(json, "java_version", java_version);

    // If we're pinging, append it
    if (isPing) {
      appendJSONPair(json, "ping", "1");
    }

    if (graphs.size() > 0) {
      synchronized (graphs) {
        json.append(',');
        json.append('"');
        json.append("graphs");
        json.append('"');
        json.append(':');
        json.append('{');

        boolean firstGraph = true;

        final Iterator<Graph> iter = graphs.iterator();

        while (iter.hasNext()) {
          Graph graph = iter.next();

          StringBuilder graphJson = new StringBuilder();
          graphJson.append('{');

          for (Plotter plotter : graph.getPlotters()) {
            appendJSONPair(graphJson, plotter.getColumnName(),
                Integer.toString(plotter.getValue()));
          }

          graphJson.append('}');

          if (!firstGraph) {
            json.append(',');
          }

          json.append(escapeJSON(graph.getName()));
          json.append(':');
          json.append(graphJson);

          firstGraph = false;
        }

        json.append('}');
      }
    }

    // close json
    json.append('}');

    // Create the url
    URL url = new URL(BASE_URL + String.format(REPORT_URL, urlEncode(pluginName)));

    // Connect to the website
    URLConnection connection;

    // Mineshafter creates a socks proxy, so we can safely bypass it
    // It does not reroute POST requests so we need to go around it
    if (isMineshafterPresent()) {
      connection = url.openConnection(Proxy.NO_PROXY);
    } else {
      connection = url.openConnection();
    }

    byte[] uncompressed = json.toString().getBytes();
    byte[] compressed = gzip(json.toString());

    // Headers
    connection.addRequestProperty("User-Agent", "MCStats/" + REVISION);
    connection.addRequestProperty("Content-Type", "application/json");
    connection.addRequestProperty("Content-Encoding", "gzip");
    connection.addRequestProperty("Content-Length", Integer.toString(compressed.length));
    connection.addRequestProperty("Accept", "application/json");
    connection.addRequestProperty("Connection", "close");

    connection.setDoOutput(true);

    if (debug) {
      System.out.println("[Metrics] Prepared request for " + pluginName + " uncompressed="
          + uncompressed.length + " compressed=" + compressed.length);
    }

    // Write the data
    OutputStream os = connection.getOutputStream();
    os.write(compressed);
    os.flush();

    // Now read the response
    final BufferedReader reader =
        new BufferedReader(new InputStreamReader(connection.getInputStream()));
    String response = reader.readLine();

    // close resources
    os.close();
    reader.close();

    if (response == null || response.startsWith("ERR") || response.startsWith("7")) {
      if (response == null) {
        response = "null";
      } else if (response.startsWith("7")) {
        response = response.substring(response.startsWith("7,") ? 2 : 1);
      }

      throw new IOException(response);
    } else {
      // Is this the first update this hour?
      if (response.equals("1") || response.contains("This is your first update this hour")) {
        synchronized (graphs) {
          final Iterator<Graph> iter = graphs.iterator();

          while (iter.hasNext()) {
            final Graph graph = iter.next();

            for (Plotter plotter : graph.getPlotters()) {
              plotter.reset();
            }
          }
        }
      }
    }
  }

  /**
   * Start measuring statistics. This will immediately create an async repeating task as the plugin
   * and send the initial data to the metrics backend, and then after that it will post in
   * increments of PING_INTERVAL * 1200 ticks.
   *
   * @return True if statistics measuring is running, otherwise false.
   */
  public boolean start() {
    synchronized (optOutLock) {
      // Did we opt out?
      if (isOptOut()) {
        return false;
      }

      // Is metrics already running?
      if (task != null) {
        return true;
      }

      // Begin hitting the server with glorious data
      task = plugin.getServer().getScheduler().runTaskTimerAsynchronously(plugin, new Runnable() {

        private boolean firstPost = true;

        public void run() {
          try {
            // This has to be synchronized or it can collide with the disable method.
            synchronized (optOutLock) {
              // Disable Task, if it is running and the server owner decided to opt-out
              if (isOptOut() && task != null) {
                task.cancel();
                task = null;
                // Tell all plotters to stop gathering information.
                for (Graph graph : graphs) {
                  graph.onOptOut();
                }
              }
            }

            // We use the inverse of firstPost because if it is the first time we are posting,
            // it is not a interval ping, so it evaluates to FALSE
            // Each time thereafter it will evaluate to TRUE, i.e PING!
            postPlugin(!firstPost);

            // After the first post we set firstPost to false
            // Each post thereafter will be a ping
            firstPost = false;
          } catch (IOException e) {
            if (debug) {
              Bukkit.getLogger().log(Level.INFO, "[Metrics] " + e.getMessage());
            }
          }
        }
      }, 0, PING_INTERVAL * 1200);

      return true;
    }
  }

  /**
   * Represents a custom graph on the website
   */
  public static class Graph {

    /**
     * The graph's name, alphanumeric and spaces only :) If it does not comply to the above when
     * submitted, it is rejected
     */
    private final String name;

    /**
     * The set of plotters that are contained within this graph
     */
    private final Set<Plotter> plotters = new LinkedHashSet<Plotter>();

    private Graph(final String name) {
      this.name = name;
    }

    /**
     * Add a plotter to the graph, which will be used to plot entries
     *
     * @param plotter the plotter to add to the graph
     */
    public void addPlotter(final Plotter plotter) {
      plotters.add(plotter);
    }

    @Override
    public boolean equals(final Object object) {
      if (!(object instanceof Graph)) {
        return false;
      }

      final Graph graph = (Graph) object;
      return graph.name.equals(name);
    }

    /**
     * Gets the graph's name
     *
     * @return the Graph's name
     */
    public String getName() {
      return name;
    }

    /**
     * Gets an <b>unmodifiable</b> set of the plotter objects in the graph
     *
     * @return an unmodifiable {@link java.util.Set} of the plotter objects
     */
    public Set<Plotter> getPlotters() {
      return Collections.unmodifiableSet(plotters);
    }

    @Override
    public int hashCode() {
      return name.hashCode();
    }

    /**
     * Called when the server owner decides to opt-out of BukkitMetrics while the server is running.
     */
    protected void onOptOut() {
    }

    /**
     * Remove a plotter from the graph
     *
     * @param plotter the plotter to remove from the graph
     */
    public void removePlotter(final Plotter plotter) {
      plotters.remove(plotter);
    }
  }

  /**
   * Interface used to collect custom data for a plugin
   */
  public static abstract class Plotter {

    /**
     * The plot's name
     */
    private final String name;

    /**
     * Construct a plotter with the default plot name
     */
    public Plotter() {
      this("Default");
    }

    /**
     * Construct a plotter with a specific plot name
     *
     * @param name the name of the plotter to use, which will show up on the website
     */
    public Plotter(final String name) {
      this.name = name;
    }

    @Override
    public boolean equals(final Object object) {
      if (!(object instanceof Plotter)) {
        return false;
      }

      final Plotter plotter = (Plotter) object;
      return plotter.name.equals(name) && plotter.getValue() == getValue();
    }

    /**
     * Get the column name for the plotted point
     *
     * @return the plotted point's column name
     */
    public String getColumnName() {
      return name;
    }

    /**
     * Get the current value for the plotted point. Since this function defers to an external
     * function it may or may not return immediately thus cannot be guaranteed to be thread friendly
     * or safe. This function can be called from any thread so care should be taken when accessing
     * resources that need to be synchronized.
     *
     * @return the current value for the point to be plotted.
     */
    public abstract int getValue();

    @Override
    public int hashCode() {
      return getColumnName().hashCode();
    }

    /**
     * Called after the website graphs have been updated
     */
    public void reset() {
    }
  }
}
